President Obama told the nation last night that with modest effort and risk, they can stop children from being gassed in Syria.

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PRESIDENT BARACK OBAMA: I believe we should act. That's what makes America different. That's what makes us exceptional.

INSKEEP: The president also said America should wait to see if a diplomatic effort works out.

MONTAGNE: Russia and Syria have said they're willing for Syria to surrender its chemical weapons. And the president doesn't have the votes in Congress to support a strike, anyway.

INSKEEP: We're going to try to understand a confusing situation this morning. We've called on Nicholas Burns, who held top diplomatic posts under Democratic and Republican presidents.

Ambassador Burns, welcome back to the program.

NICHOLAS BURNS: Thanks very much.

MONTAGNE: And, Ambassador Burns, let's start with what you think of this diplomatic opening. Does it seem real to you?

BURNS: I think it is real. I mean, the president, I think, made an effective case last night why Assad is culpable. But he also put us firmly on the diplomatic path. But that path has some problems with it, and the United States and Russia are not exactly in step with each other as it begins.

INSKEEP: We noticed on Twitter last night that you were surprised the president didn't outline what the United States says an agreement should look like. So what does the U.S. actually have the leverage to demand here?

BURNS: Well, I think I know why he didn't list the conditions by which the United States could accept it. He doesn't want to pick a fight with President Putin now, because the U.S. and Russian positions are far apart. And I think he wants to leave Secretary Kerry - who's going to be negotiating this agreement with the Russian foreign minister in Geneva the next two days - he wants to leave him some flexibility.

But here are the differences: Will the agreement be binding? Russia was prepared to introduce yesterday a so-called presidential statement up in New York at the Security Council, whereas the U.S. and France want a binding resolution Chapter 7. What that means is that every nation-state - most especially including Syria - will have to abide by. That's the first disagreement.

Second, will there be an enforcement mechanism? Meaning will the United States be given the right, along with other countries, to enforce this agreement by military force should Syria tried to renege? And the reason for that is that Syria has been very untrustworthy. Syria has not admitted it's had these chemical weapons for decades. And so the feeling is if you don't have an enforcement mechanism, the Syrians could just play out the clock and never implement the agreement.

And there's also a disagreement, I think, at this point, the length of time by which Syria would have to comply with this agreement. So, in other words, if the inspectors arrived, the Syrian government has 15 days or 30 days to turn the chemical weapons over to them.

MONTAGNE: How much does it matter exactly how the agreement is made, if it's made?

BURNS: I think the devil will be in the details, here, the specific aspects of this which determines whether it's a deal that the United States or Russia can live with. And certainly, from an American perspective, it would be difficult to walk into an open-ended agreement and not have the ability to enforce its conclusion. There's no reason for the Assad government to give up the chemical weapons until it's absolutely forced to do so.

I think President Obama has a right to suggest the only reason we're at this place is because President Obama made a credible threat of force. The Syrian government is always looked on its chemical weapons as one of its national assets in the very tough neighborhood in which it lives. So I don't think they'll give up these weapons unless their feet are held to the fire.

INSKEEP: Ambassador, I want to ask about one other thing. The president last night actually said we do not want to remove dictators by force. And I wonder, is there a brutal reality here? I mean, if the United States deals with Assad, the United States is then negotiating with a dictator. And part of that is acknowledging that he's probably going to keep his job.

BURNS: U.S. rhetoric for a long time has been that Assad should go. But, obviously, that's not our policy, and I think rightly so. We're not willing to invade the country, as we did in Iraq in 2003, not willing to remove him by force. And so, therefore, we're going to have to deal with Assad. And I think it's important, obviously, to deal with him on the issue of chemical weapons.

But there's a huge humanitarian crisis now. A hundred and ten thousand people killed, six million people displaced. We'll have to deal with him on that. And at some point, the United States is going to have to move - with the Arab countries, Russia, maybe even Iran - to impose a ceasefire, because this civil war is tearing the country apart, and it's threatening to engulf Jordan and Lebanon and Turkey, as well.